The Kremlin on June 15 is hosting a reception that marks the start of weeklong gathering of power energy sector leaders from around the world.

The World Petroleum Congress -- an event that takes place every three years -- takes on particular importance in Moscow this year amid Russia's conflict with the West over the Ukraine crisis.

Rising oil prices since the seizure of territory in Iraq by an Al-Qaeda splinter group -- the Islamic State in Iraq and the Levant -- also has focused attention on the event.

OPEC Secretary-General Abdullah el-Badri is expected to attend along with some 5,000 delegates from public and private firms in 65 countries -- including the chief executive of Britain’s BP, Bob Dudley, and bosses from Russia’s Gazprom and Rosneft.

Russian President Vladimir Putin plans to speak to delegates in Moscow on June 16.